Theresa May, then home secretary, at the Conservative party conference in Manchester in 2011.
Photograph: Jeff J Mitchell/Getty Images

To the politicians who presided over a long-term policy to use every means possible to reject and eject as many people from the UK, regardless of extenuating circumstances or status (up to and including whether they came to the country as British subjects or citizens), the Windrush scandal appears to be an aberration. Amber Rudd called the treatment “appalling”, as if she had no responsibility for it as the current home secretary. Caroline Nokes, the immigration minister, revealed that there had been deportations but that she did not know how many, and that the situation “as a minister” had “appalled” her.

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It’s all just a quirk of the system you see, a mechanical fault, an unintended consequence, is the narrative. But a miscarriage at the scale that every day seems to grow more bewildering is too large to be attributed to clerical error or incompetence. It is in the official documents. The Home Office annual report from last year stated that: “In January 2016, we broadened our engagement activity in priority countries to maximise returns of all nationals in the UK illegally.” In 2014 the government removed a key protection from the statute books for some British residents of the Windrush generation who could face deportation. Official handbooks were printed, giving instructions to deportees. One clause in particular is a smoking gun, “try to be Jamaican – use local accents and dialect (overseas accents can attract unwanted attention)”. The Home Office had created a whole guidebook based on the premise that it was sending people to a land that was foreign to them.

It is bewildering to watch May have the gall, even in the face of such an obvious breadcrumb trail, to attempt to minimise the problem and urge people to engage in this doublethink. During prime minister’s questions this week she offered a robotic apology but stopped short of accountability, or a promise of reform. But for her to admit that this is just one example of the immigration policies the Home Office has been instructed to execute would rightly invalidate the whole system and trigger a loss of faith. And it would mean holding May accountable. Little has animated the bloodless May more than her hostility to immigration, and under her leadership the Home Office became a ruthless tool of persecution. Never mind Rudd, merely a pliant executor of May’s obsession with the “tens of thousands” net migration target. If the buck stops anywhere, it stops with the prime minister.

The room was full of people whose lives had been thrown into turmoil by lost papers, glitches and glacial incompetence

During my own long battle with the Home Office to secure residency, I spent many hours in Croydon. I went on one occasion to withdraw my passport, which had languished unprocessed for months, to travel to see my sick mother. Driven wild with fear that I would not be able to see her if the unthinkable happened, I was ready to risk not being allowed back in the country. The waiting room was a holding pen of quiet individual tragedies, full of people whose personal and professional lives had been thrown into turmoil by loss of documents, technical glitches and glacial incompetence. The cruelty we all experienced was not a bug, it was a feature.

The scandal of the Windrush generation is the kind of thing that happens when this rot sets in so deep that the infrastructure of a civilised society begins to fall apart. The rise in the number of the persecuted is analogous to the doubling in deaths of homeless people. There is only so much austerity an economy can take before the human toll rises. And there is only so much ideological fixation on “sending people home” before we are deporting grandmothers who arrived in this country when they were children.

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And make no mistake, it is ideological. The Conservative party has been consistent in its aggressive immigration policy since 2010, when David Cameron decided that a tough stance on immigration was a flagship party offering to its base supporters. No ifs, no buts, he said. Detention, deportation and NHS treatment refusal is the culmination of the party’s most lucid positions. It is not incompetence, it is not even malice. It is an enthusiastic strategy that over the past decade has become a cornerstone, a defining element of Conservative governments. An immigration policy, very much like austerity, unafraid to be brutal if the deserving, whether they are the “indigenous population” of the country or hardworking taxpayers, are to be protected from those who are after a “free ride”.

There has been no bureaucratic snafu. The only miscalculation was that everyone got a little bit cocky, and who can blame them. The error was that the dragnet picked up some people who fall into a popular sympathy sweet spot. The elderly ones who came here from the Commonwealth to rebuild Britain and who even the Daily Mail can look kindly upon. They appeal to a patrician nostalgia and have a humanising narrative that others who come to this country in different circumstances do not enjoy. An apology and exceptions made for Windrush cases alone is not enough. If we are to be content with only this, then the government’s furtive shimmy away from the crime scene will be successful, and the Home Office’s daily violations of human rights will continue. If we are to prevent the assaults against those we can relate to, we must also be angry for those we cannot.

• Nesrine Malik is a Guardian columnist. She is a former private equity investor